Brake control systems are in common use to help drivers control steep descents, start uphill, and stay on the road when traction degrades. The Crawl Control vehicle brake system, recently introduced by Toyota Motor Corp., Susono, Japan, and ADVICS Co., LTD., Kariya, Japan, is the only one to unite existing control measures in a comprehensive system for off-road driving conditions. Using four-wheel-drive's low-range transfer case, Crawl Control modulates brake torque and drive torque to simulate a limited slip differential effect. The gas pedal is unnecessary-calculations sent to the engine computer, based on dynamics such as wheel and vehicle speed, lateral acceleration, yaw rate, and torque outputs, hold speed constant. Crawl Control 's ability to respond to inputs faster than the driver can help reduce the likelihood of getting stuck and reduce component stress on the vehicle.